U.S. patent application number 15/117416 was filed with the patent office on 2017-01-19 for tensioning device for a strapping device.
This patent application is currently assigned to Orgapack GmbH. The applicant listed for this patent is Orgapack GmbH. Invention is credited to Hans Huber, Dimitrios Takidis, Roland Widmer.
Application Number | 20170015451 15/117416 |
Document ID | / |
Family ID | 52697174 |
Filed Date | 2017-01-19 |
United States Patent
Application |
20170015451 |
Kind Code |
A1 |
Huber; Hans ; et
al. |
January 19, 2017 |
TENSIONING DEVICE FOR A STRAPPING DEVICE
Abstract
The present disclosure relates to a tensioning device of a
strapping device for strapping packaged material with a strap. The
tensioning device includes a tensioning wheel operatively
connectable to a drive device to rotate the tensioning wheel about
a rotational axis. The tensioning wheel has a circumferential
surface configured to engage the strap. The tensioning device also
includes a movable spacer provided on the tensioning wheel in the
region of the circumferential surface of the tensioning wheel. The
spacer is movable between a first position in which part of the
spacer is a first distance from the rotational axis and a second
position in which the part of the spacer is a second different
distance from the rotational axis. The spacer projects beyond the
circumferential surface of the tensioning wheel in at least one of
the positions.
Inventors: |
Huber; Hans; (Hagglingen,
CH) ; Takidis; Dimitrios; (Zurich, CH) ;
Widmer; Roland; (Bremgarten, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Orgapack GmbH |
Dietikom |
|
CH |
|
|
Assignee: |
Orgapack GmbH
Diektikon
CH
|
Family ID: |
52697174 |
Appl. No.: |
15/117416 |
Filed: |
February 10, 2015 |
PCT Filed: |
February 10, 2015 |
PCT NO: |
PCT/CH2015/000013 |
371 Date: |
October 6, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 88/06 20130101;
B65B 13/22 20130101; B65B 13/06 20130101; G06F 40/186 20200101;
G09G 2354/00 20130101; G06K 9/222 20130101; G09G 5/12 20130101 |
International
Class: |
B65B 13/22 20060101
B65B013/22; B65B 13/06 20060101 B65B013/06 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 10, 2014 |
CH |
181/14 |
Feb 10, 2014 |
CH |
182/14 |
Feb 10, 2014 |
CH |
183/14 |
Claims
1-21. (canceled)
22. A tensioning device for an apparatus for strapping packaged
articles with a strapping band, the tensioning device comprising: a
tensioning wheel operatively connectable to a drive device to
rotate the tensioning wheel about an axis of rotation, the
tensioning wheel having a circumferential surface configured to
engage the strapping band; and a spacer element mounted on the
tensioning wheel such that the spacer element is movable between:
(1) a first position in which at least part of the spacer element
has a first spacing from the axis of rotation and projects beyond
the circumferential surface of the tensioning wheel; and (2) a
second position in which the at least part of the spacer element
has a second spacing from the axis of rotation, wherein the second
position is different from the first position and the second
spacing is different from the first spacing.
23. The tensioning device of claim 22, wherein when in the second
position, the at least part of the spacer element is substantially
flush with the circumferential surface of the tensioning wheel.
24. The tensioning device of claim 22, wherein the spacer element
is movable from the first position to the second position via
application of force to the at least part of the spacer
element.
25. The tensioning device of claim 22, wherein the spacer element
is coaxial with the tensioning wheel and rotatable with the
tensioning wheel.
26. The tensioning device of claim 22, wherein the spacer element
is oriented with a longitudinal extent at least substantially
parallel to the circumferential direction of the circumferential
surface.
27. The tensioning device of claim 22, wherein the spacer element
is disposed in a groove defined in the circumferential surface.
28. The tensioning device of claim 27, wherein the groove extends
over at least part of the circumferential surface and the spacer
element includes at least part of a ring.
29. The tensioning device of claim 27, which includes a resiliently
elastic element disposed in the groove and against which the spacer
element bears.
30. The tensioning device of claim 27, wherein the tensioning wheel
and the spacer element are positioned and arranged such that,
during the tensioning process, the tensioning wheel rotates and, in
relation to a positionally static polar coordinate system of the
tensioning wheel, the strapping band forces the spacer element into
the groove at least at the substantially always identical
circumferential section of the tensioning wheel, whereas, at the
remaining circumferential section against which the strapping band
does not bear, the spacer element projects from the circumferential
surface.
31. The tensioning device of claim 22, wherein the spacer element
is positioned approximately centrally in relation to the width of
the circumferential surface of the tensioning wheel.
32. A strapping device for strapping packaged articles with a
strapping band, the strapping device comprising: a tensioning
device comprising: (a) a tensioning wheel operatively connectable
to a drive device to rotate the tensioning wheel about an axis of
rotation, the tensioning wheel having a circumferential surface
configured to engage the strapping band; and (b) a spacer element
mounted on the tensioning wheel such that the spacer element is
movable between: (1) a first position in which at least part of the
spacer element has a first spacing from the axis of rotation and
projects beyond the circumferential surface of the tensioning
wheel; and (2) a second position in which the at least part of the
spacer element has a second spacing from the axis of rotation,
wherein the second position is different from the first position
and the second spacing is different from the first spacing; and a
fastening device configured to join two sections of the strapping
band.
33. The strapping device of claim 32, wherein during a tensioning
process, the strapping band exerts a first force on the spacer
element to cause the spacer element to move from the first position
to the second position such that the at least part of the spacer
element is substantially flush with the circumferential surface of
the tensioning wheel and the strapping band contacts the
circumferential surface of the tensioning wheel, and wherein during
a band retraction process, the strapping band exerts a second force
on the spacer element, the second force being less than the first
force and insufficient to cause the spacer element to move from the
first position to the second position.
34. The strapping device of claim 32, which includes a band
advancement/retraction roller, a counterpart roller, and a motor
operably connected to the band advancement/retraction roller to
drive the band advancement/retraction roller in two different
directions of rotation and also operably connected to the
tensioning wheel to drive the tensioning wheel in at least one of
the directions of rotation, wherein the counterpart roller is
movable between a first position in which the counterpart roller
contacts the band advancement/retraction roller and a second
position in which the counterpart roller contacts the tensioning
wheel.
35. The strapping device of claim 34, wherein the motor is the only
motor operably connected to both the tensioning wheel and the band
advancement/retraction roller.
36. The strapping device of claim 32, which includes a clearance
device configured to increase spacing between a counterpart roller
and a motor-driven roller provided for imparting a band
movement.
37. The strapping device of claim 36, wherein the increased spacing
is greater than a thickness of the strapping band.
38. A strapping device for strapping packaged articles with a
strapping band, the strapping device comprising: a tensioning
device comprising: (a) a tensioning wheel operatively connectable
to a drive device to rotate the tensioning wheel about an axis of
rotation, the tensioning wheel having a circumferential surface
configured to engage the strapping band; and (b) a spacer element
mounted on the tensioning wheel such that the spacer element is
movable between: (1) a first position in which at least part of the
spacer element has a first spacing from the axis of rotation and
projects beyond the circumferential surface of the tensioning
wheel; and (2) a second position in which the at least part of the
spacer element has a second spacing from the axis of rotation,
wherein the second position is different from the first position
and the second spacing is different from the first spacing; a
fastening device configured to join two sections of the strapping
band; and an encircling strapping channel configured to guide the
strapping band during a strapping process.
39. The strapping device of claim 38, wherein during a tensioning
process, the strapping band exerts a first force on the spacer
element to cause the spacer element to move from the first position
to the second position such that the at least part of the spacer
element is substantially flush with the circumferential surface of
the tensioning wheel and the strapping band contacts the
circumferential surface of the tensioning wheel, and wherein during
a band retraction process, the strapping band exerts a second force
on the spacer element, the second force being less than the first
force and insufficient to cause the spacer element to move from the
first position to the second position.
40. The strapping device of claim 38, which includes a band
advancement/retraction roller, a counterpart roller, and a motor
operably connected to the band advancement/retraction roller to
drive the band advancement/retraction roller in two different
directions of rotation and also operably connected to the
tensioning wheel to drive the tensioning wheel in at least one of
the directions of rotation, wherein the counterpart roller is
movable between a first position in which the counterpart roller
contacts the band advancement/retraction roller and a second
position in which the counterpart roller contacts the tensioning
wheel.
41. The strapping device of claim 38, which includes a clearance
device configured to increase spacing between a counterpart roller
and a motor-driven roller provided for imparting a band movement.
Description
[0001] This application is a national stage entry of
PCT/CH2015/000013, filed on Feb. 10, 2015, which claims priority to
and the benefit of Switzerland Patent Application Nos.: (1) 183/14,
filed on Feb. 10, 2014; (2) 182/14, filed on Feb. 10, 2014; and (3)
181/14, filed on Feb. 10, 2014, the entire contents of each of
which are incorporated herein by reference.
[0002] The present disclosure relates to a tensioning device of a
strapping apparatus for the strapping of packaged articles with a
strapping band, in particular with a plastics strapping band, which
is equipped with a tensioning wheel which is operatively connected
or operatively connectable to a drive device to set the tensioning
wheel in a rotational movement about an axis of rotation, wherein
the tensioning wheel has a circumferential surface which is
designed for engaging into the strapping band. In the context of
the present disclosure, the tensioning device may be provided both
for static strapping apparatuses and for mobile, in particular
portable, strapping apparatuses.
[0003] Strapping apparatuses of said type may be formed inter alia
as a static installation which is utilized for equipping relatively
large packaged articles, or multiple individual packaged articles
placed together to form a packaged article unit, with one or more
band straps. The band straps are normally formed from a band which
is drawn from a supply roll and laid as a ring-shaped strap around
the packaged article. For this purpose, the strapping band is shot
with its free end first into a channel of the strapping apparatus,
which channel surrounds the packaged article, with a spacing, in
the manner of a portal or in ring-shaped fashion. Normally, as soon
as the band end has reached a particular point in the channel, the
band end is clamped and the band is then retracted again. As a
result, the loop of the strapping band is tightened and the band
passes out of the channel and into contact with the packaged
article. Subsequently, a band tension is applied to the band, and
the band ring is equipped with a fastening and is cut off from the
supply roll. As strapping band, use is made both of metallic bands
and of plastics bands. The strapping apparatuses are normally
adapted to the strapping band types used therewith, in particular
with regard to the connecting device by way of which two band
layers, which lie one over the other in sections, of the strapping
bands can be non-detachably connected to one another.
[0004] In the case of previously known solutions, during the
retraction of the strapping band, the band of the loop is generally
retracted at high speed in a direction opposite to the advancing
direction in which the band was previously shot into the channel.
It is normally also the case that the tensioning wheel of the
tensioning device is arranged in said retraction path, by means of
which tensioning wheel the tensioning process is only subsequently
performed. Since the tensioning wheel is normally not driven, and
is thus at a standstill, during the retraction process, there is
the risk of the strapping band being guided or pulled over the
tensioning wheel during the band retraction movement. As a result
of the contact and the relative movement between the tensioning
wheel and the strapping band, the strapping band can be damaged by
the tensioning wheel. This risk is all the greater if the
circumferential surface of the tensioning wheel is not smooth but
is equipped with a geometrically defined or undefined roughened
surface, such as for example a fluting, knurling or toothing, such
as is common for improving the engagement conditions and for the
avoidance of slip in the case of tensioning wheels. As a result of
such damage to the strapping band generated by the tensioning
wheel, the tensile strength of the strapping band can be reduced in
the region of the damage, such that the band tears under the
imparted tensile stress. Further disadvantages of such engagement
can be seen in the friction-induced reduction of the band
retraction speed and in the abrasion caused by the contact of the
band with the rough surface of the tensioning wheel during the band
retraction phase.
[0005] The present disclosure is therefore based on the object of
improving a strapping device for strapping packaged articles with a
strapping band such that disadvantages that arise as a result of
the relative speed between the tensioning wheel and the band during
the band retraction phase are as far as possible avoided.
[0006] Said object is achieved according to the present disclosure
by way of a tensioning device of the type mentioned in the
introduction in that, in the region of the circumferential surface
of the tensioning wheel, there is provided on the tensioning wheel
at least one movable spacer element which can be arranged in a
first position and in a second position that differs from said
first position, wherein, in the first position, the spacer element
can be arranged at least in sections with a first spacing to the
axis of rotation of the tensioning wheel and, in the second
position, can be arranged with a second spacing, at least in
sections, to the axis of rotation of the tensioning wheel, the
first spacing differs here from the second spacing, and the spacer
element, in at least one of the two positions, projects beyond the
circumferential surface of the tensioning wheel. In this context,
the spacing to the axis of rotation may be understood to mean a
spacing of a region of the respective spacer element, which region
which is provided for contact with the strapping band at least in
one of the two positions, to the axis of rotation. The present
disclosure thus makes it possible, by way of the at least one
spacer element which is movable relative to the tensioning wheel,
for the strapping band to be prevented from coming into contact
with the surface of the tensioning wheel when the spacer element
assumes its position in which it projects at least in sections
beyond the circumferential surface of the tensioning wheel.
[0007] In one embodiment of the present disclosure, it may be
provided that, by way of a force externally applied to the spacer
element of the tensioning wheel, the spacer element can be
transferred at least in sections from the position with the
relatively large radial spacing to the axis of rotation into the
other position with the relatively small radial spacing to the axis
of rotation. The expression "externally applicable" may in this
case be understood in particular to mean that the force is applied
by an element which does not belong to the tensioning wheel or to
the spacer element itself, in particular by the strapping band. The
spacer element may be in the form of a passive element with regard
to its change in position or the change in its geometrical shape.
Since it is thus the case in such embodiments of the present
disclosure that there is no need for a drive of the tensioning
wheel to be provided for the generation of the change in position
or shape of the spacer element, the tensioning wheel can be of
structurally simple form despite the realization of the function
according to the present disclosure.
[0008] A structurally simple and nevertheless compact embodiment of
the present disclosure may provide that the spacer element is
arranged so as to be rotatable together with the tensioning wheel.
The at least one spacer element may be movable relative to the
tensioning wheel itself, wherein changes in position of the at
least one spacer element can take place, and are possible, in
particular during a rotation of the tensioning wheel.
[0009] It may be provided that the at least one spacer element
assumes its first position during the band retraction phase, such
that, during the band retraction phase, the strapping band is
arranged against the at least one spacer element of the tensioning
wheel and thus with a spacing to the circumferential surface of the
tensioning wheel. The band is thus ideally prevented by the spacer
element from coming into contact with the circumferential surface
of the tensioning wheel during the band retraction phase. If such
contact is not entirely avoidable, said contact should however at
least be reduced to the greatest possible extent by the spacer
element. For the tensioning phase or the tensioning process, it is
by contrast possible, in certain embodiments of the present
disclosure, for the at least one spacer element to be moved with at
least one of its sections into the second position thereof in
which, at those points of the circumferential surface at which the
tensioning wheel is looped around by the strapping band, said at
least one spacer element is arranged no higher than the same height
as the circumferential surface, or is arranged lower than said
circumferential surface. In this way, the spacer element leaves the
circumferential surface free for the desired contact with the
circumferential surface during the tensioning process.
[0010] The at least one spacer element may be arranged in different
orientations relative to the circumferential surface. Here, an
orientation of the spacer element is parallel to the
circumferential direction of the tensioning wheel. In this way, it
is possible, with particularly little outlay in terms of
construction, for the function of the spacer element to be ensured
along the entire circumference of the tensioning wheel.
[0011] As a spacer element, both passive and active spacer elements
may be provided for the purposes of moving the at least one spacer
element into its two positions. Active elements may be understood
as elements which perform a change in position or shape
automatically, for example elements which perform self-generating
changes in position and/or shape of the spacer element through the
use of hydraulic or pneumatic energy or the use of electrical or
magnetic energy. By contrast, however, in certain embodiments
passive spacer elements are preferred, that is to say spacer
elements which have a change in position and/or shape externally
forcibly imparted to them, without the spacer element itself
contributing to this. A change in position or shape may be realized
for example by way of a counterpart roller which imparts a pressure
force in the direction of the tensioning wheel and presses the band
against the spacer element. In the presence of a correspondingly
high force coordinated with the characteristics of the spacer
element, it is possible in this way for the region of the spacer
element to be provided with a smaller spacing to the axis of
rotation of the tensioning wheel than in the unloaded state. The
change in spacing may be utilized to the effect that, in the region
of the counterpart roller, the strapping band bears now not against
the spacer element but against the circumferential surface of the
tensioning wheel.
[0012] Certain embodiments of the present disclosure are in
particular embodiments in which there is no need for control of the
times at which changes in position of the spacer element are to be
performed. One embodiment of a passive spacer element may therefore
provide that the forces exerted by the band on the tensioning wheel
and thus also on the spacer element are themselves utilized to
perform a change in position. Here, a particularly advantageous
embodiment may provide that the forces of different magnitude
during the band retraction phase and the tensioning phase are
utilized to determine whether a change in position and/or shape
should be initiated. A switching process is not necessary for this
purpose; the change in position and/or shape may be realized, and
also reversed, automatically. For this purpose, the spacer element
may be designed such that the force exerted by the band on the
tensioning wheel during the band retraction phase is not sufficient
to move the spacer element into its second position. The relatively
higher forces that are exerted by the band on the tensioning wheel
during the tensioning process are however suitable, by way of
correspondingly suitable configuration of the spacer element, for
moving said spacer element into its second position in which
contact is then realized between the strapping band and the
circumferential surface. In this embodiment, neither additional
energy nor monitoring or control of the process are necessary. An
embodiment of the present disclosure which is uncomplicated in
terms of construction but which is nevertheless functionally
reliable is thus realized.
[0013] One embodiment of the present disclosure may provide both a
counterpart roller, which imparts force in the direction of the
tensioning wheel, and the utilization of the band for generating
the change in position. In this way, it is possible for the change
in position and/or shape of the spacer element to be realized in a
particularly functionally reliable manner. Here, it may be
advantageous if, in particular at the start of the tensioning
phase, the band is forced against the spacer element by way of a
counterpart roller or some other suitable element and, in this way,
the spacer element is, at least in the region of the counterpart
roller, forced back such that the band comes into contact with the
circumferential surface. In this way, the band enters into
engagement with the tensioning wheel, whereby it is possible to
commence with increasing the band tension. As a result of this, the
band begins to lie against the spacer element over an at least
substantially predetermined wrap angle corresponding to its
provided band guidance around the tensioning wheel. By way of an
increase of the band tension, it is then also possible for the
pressure force to be increased to a magnitude sufficient to force
the spacer element back in the region of contact with the band, in
such a way that the band is, over its wrap angle on the tensioning
wheel, in contact with the circumferential surface of said
tensioning wheel. Here, it is particularly advantageous for the
spacer element to be forced back to such an extent that the spacer
element, at least over a part of the wrap angle (and in certain
embodiments substantially over the entire wrap angle) does not
project beyond the contact region of the circumferential surface
with the band. It is thus possible for the tensioning wheel to
remain in engagement by way of its non-smooth circumferential
surface even in the presence of further increasing band tension,
and the band tension can be increased up to an intended value.
[0014] In this context, the expression "do not project beyond the
circumferential surface" can also be understood to encompass
arrangements in which the spacer element projects only slightly
beyond the circumferential surface, and the strapping band, for
example owing to its elasticity and deformability, can come into
contact with the circumferential surface despite said small
projecting length.
[0015] In another embodiment of the present disclosure, the
circumferential surface of the tensioning wheel may, at least over
a part of the length of the circumference, be equipped with a
groove in which, as a constituent part of the spacer element, there
may be arranged a ring element which can be arranged at least in
sections in different positions. Here, the ring element may
advantageously be arranged in a first position, in which it is
elevated at least in sections in relation to the circumferential
surface, and in a second position, in which the ring element, at
least in sections, does not project beyond the circumferential
surface.
[0016] Basically, a multiplicity of different solutions is
conceivable by way of which the spacer element, such as for example
the ring element, prevents the strapping band from coming into
contact with the surface, which is intentionally kept non-smooth,
of the tensioning wheel. A particularly advantageous solution may
provide that the ring element extends substantially over the entire
circumference of the tensioning wheel and is arranged in a groove
which extends over the circumference of the tensioning wheel. In an
expedient refinement of the present disclosure, it may be possible
for the ring element to be forced into the groove by the strapping
band under pressure loading, such that, owing to the ring element
being forced back in this way, it is the case along a wrap angle
that the ring element no longer projects beyond the circumferential
surface, and the strapping band can come into contact with the
circumferential surface of the tensioning wheel. The ring element
may be designed so as to be forced back into the groove in the
described manner only under the action of a certain minimum force
acting on the ring element. Said minimum force may be predetermined
such that it is reached during the tensioning process but not
during the band retraction process.
[0017] In a further particular advantageous embodiment, it is
possible, through utilization of resilient elasticity, for the ring
element, or other embodiments of the spacer element, to be restored
immediately and automatically when correspondingly relieved of the
band pressure after having previously been subjected to load. To
achieve this, the ring element, or some other embodiment of the
spacer element, may itself be of resiliently elastic form. In
further embodiments, there may be provided, in addition to the
possibly at least substantially rigid or not adequately elastic
spacer element, at least one resiliently elastic element, such as
for example one or more O-rings or other spring elements, which
impart a returning action to the spacer element. Aside from a high
level of functional reliability, these solutions also make it
possible to avoid a supply of external energy.
[0018] Finally, in a further embodiment of the tensioning device,
during the tensioning process, the tensioning wheel rotates and, in
relation to a positionally static polar coordinate system of the
tensioning wheel, the spacer element is forced into the groove at
the at least substantially always identical circumferential section
of the tensioning wheel, whereas, at the remaining circumferential
section, against which the strapping band does not bear, the spacer
element projects in relation to the circumferential surface.
[0019] The above-stated object is furthermore achieved by way of a
strapping device which is equipped with one of the tensioning
devices according to the present disclosure.
[0020] Another embodiment of the present disclosure--which may also
be of independent significance independently of the number of
wheels, rollers and motors used for the imparting of movements to
the band and independently of the design of the tensioning
wheel--may provide an actuable means by which at least one wheel of
a wheel pair of the advancing device can be switched into a state
in which the strapping band can be displaced between the wheel pair
in a direction opposite to the band advancement movement, without a
corresponding motor drive movement being transmitted to the
strapping band. With the present disclosure, provision is thus made
for the state of the wheel pair to be changed from a state in which
the band is clamped between said wheels, which state permits in
particular the advancement of the band, into a state in which the
band can move through between the wheel pair regardless of a driven
movement of a wheel of the wheel pair. According to the present
disclosure, the clamping state between the wheel pair, which
clamping state is provided for the transmission of a motor drive
movement via one of the two wheels to the strapping band, is
reduced at least to such an extent that slippage or an increased
gap can form between the band and the wheel pair. If an enlarged
gap between the circumferential surfaces of the wheels is generated
in the event of the clamping action being eliminated, said gap
should be larger than the band thickness. The clamping action may
for example be reduced simply by virtue of a pressure force with
which the two wheels are pressed against one another being reduced,
for example by way of a variably adjustable magnitude of said
pressure force. Such a reduction of the clamping action may alone
be sufficient for a strapping band to be able to move between the
wheel pairs of its own accord.
[0021] The possibility of movement of the strapping band between
the wheels of the wheel pair may however alternatively also be
realized by virtue of an operative connection between a driven
wheel and its drive being eliminated, such that both wheels of the
wheel pair are rotatable freely and without a holding torque of the
drive device. Such an elimination of an operative connection may be
performed for example by way of a switchable clutch in the drive
train of the driven wheel. By way of said switchable clutch, it is
also possible for the operative connection to be restored in order
for a drive movement, in particular a band retraction movement, to
subsequently be imparted by the driven roller to the strapping band
again.
[0022] By way of free rotatability of the wheel pair, or at least
slippage or an adequately large gap between the wheels, it is made
possible for the strapping band, immediately after or even during
the generation of the band loop, to discharge excess band length of
the band loop through between the wheel pair, whereby it is sought
to as far as possible prevent the formation of a convolution. An
incipient excess band length in the strapping channel leads to
buckling in the band loop and thus to compressive and/or bending
stresses in the strapping band. Normal strapping bands exhibit a
flexural rigidity which has the effect that such bands have the
tendency to dissipate compressive and bending stresses by seeking
to assume planar and rectilinearly running orientation. This is
advantageously utilized by the present disclosure in that, through
the creation of a possibility for movement of the band through
between the wheel pair, excess band length can move in particular
of its own accord out of the band channel again between the wheels
owing to the self-relaxation of the band.
[0023] In another refinement of said further aspect of the present
disclosure, a strapping device in the case of which an advancing
movement of the band through the strapping device is provided for
the formation of a band loop and, here, the band is clamped between
a motor-driven roller and a counterpart roller, a clearance device
can be provided. According to this aspect of the present
disclosure, in the case of a strapping device, the clearance device
may be provided for performing a clearance-generating process
between the driven roller and its counterpart roller, by way of
which a spacing between the driven roller and its counterpart
roller is generated or enlarged and is subsequently reduced in size
again. In this context, therefore, the expression "generating a
clearance" may be understood to mean the generation of a
spacing.
[0024] With this measure according to said further aspect of the
present disclosure, it is possible in a particularly functionally
reliable manner for the formation of a convolution in the band
noose or loop, in particular in the region of a band drive device
of the strapping device, such as has hitherto often arisen after
the completion of the band advancement process in the case of a
high band advancement speed and can lead to malfunctions of the
strapping device, to be at least substantially avoided. Excess band
can move in the direction of the band store again of its own accord
through the gap, enlarged owing to the clearance-generating
process, between the two rollers. Such a backward movement of a
band section through the enlarged gap between the two rollers may
take place automatically, in particular owing to the impetus or the
kinetic energy present in the band owing to the band advancement
that has previously taken place and the flexural rigidity of the
band, without the need for a corresponding motor-generated drive
movement to be imparted to the band in the same direction.
[0025] It is advantageously possible for the clearance-generating
process between the two rollers to be eliminated again before the
band retraction process effected by motor drive movement, and for
the two rollers to be placed in contact with one another again. The
clearance-generating process is thus performed at a time between
the band advancement process and the band retraction process. A
time overlap between the band advancement process and/or the band
retraction process, on the one hand, and the clearance-generating
process, on the other hand, is possible here but is not
imperative.
[0026] In a further expedient embodiment of the present disclosure
according to this aspect, the non-motor-driven counterpart roller
may be arranged on a rotatable eccentric. Here, the
clearance-generating device may act on the eccentric in order, by
way of rotation of the eccentric and the eccentricity, to generate
between the two rollers a gap which is greater than the band
thickness. After the completion of the clearance-generating
process, the eccentric can be rotated in the then opposite
direction again, whereby the two rollers clamp the band between
them again and a band retraction process can be performed by way of
the two rollers. Said embodiment of the present disclosure has
inter alia the advantage that a fast movement of the counterpart
roller for the generation of a spacing to the driven roller, and an
advancing movement toward the driven roller again, are possible by
way of an eccentric with a relatively small structural space
requirement. In other embodiments of the present disclosure, the
spacing between the two rollers for the clearance-generating
process may self-evidently also be realized in some other way, for
example by way of a pivoting movement or a linear movement of at
least one of the two rollers.
[0027] In a further expedient embodiment of the present disclosure,
it may be provided that the clearance-generating movement is
realized by way of a linearly movable driven element such as for
example a stroke-performing piston. Such stroke-performing elements
are available in a variety of forms and with different drive
principles. With such stroke-performing elements, it is possible
the drive movement to form particularly functionally reliable
clearance-generating devices. Furthermore, with such drive
elements, it is also possible with relatively little outlay for
existing strapping apparatuses to be retrofitted with a
clearance-generating device.
[0028] Further embodiments of the present disclosure will emerge
from the claims, from the description and from the drawing. The
content of disclosure of the patent claims is hereby incorporated
by reference into the description. The present disclosure will be
discussed in more detail below on the basis of exemplary
embodiments which are illustrated purely schematically in the
figures.
[0029] FIG. 1 is a highly schematized illustration of a strapping
apparatus according to the present disclosure which is equipped
with a strapping head according to the present disclosure.
[0030] FIG. 2 is a perspective illustration of a strapping head
according to the present disclosure.
[0031] FIG. 3 is a perspective illustration from above of the
strapping head from FIG. 2 integrated into a band guide of a
strapping apparatus.
[0032] FIG. 4 shows a side view of the strapping head from FIG. 2,
in the case of which a component is situated in a pivoted-out
servicing position.
[0033] FIG. 5 is a perspective partial illustration of the
strapping head from FIG. 2, with the band drive device being
illustrated.
[0034] FIG. 6 shows a front view of the band drive device from FIG.
5.
[0035] FIG. 7 is a perspective illustration of a tensioning wheel
according to the present disclosure with a partial illustration of
the knurling of the circumferential surface of the tensioning
wheel.
[0036] FIG. 8 shows a front view of the tensioning wheel from FIG.
7.
[0037] FIG. 9 is a cross-sectional illustration of the tensioning
wheel along a diameter line.
[0038] FIG. 10 shows a component of a lever mechanism for a
counterpart roller of the band drive device.
[0039] FIG. 11 shows a further component of the lever mechanism of
the counterpart roller in a perspective illustration.
[0040] FIG. 12 shows the component from FIG. 11 in a front
view.
[0041] FIG. 13 is a sectional illustration of the component from
FIGS. 11 and 12.
[0042] FIG. 14 is an exploded illustration of another exemplary
embodiment of a tensioning wheel.
[0043] FIG. 15 is a perspective illustration of the tensioning
wheel from FIG. 14.
[0044] FIG. 16 shows a front view of the tensioning wheel from
FIGS. 14 and 15.
[0045] FIG. 17 is a sectional illustration of the tensioning wheel
from FIGS. 14-16.
[0046] FIG. 18 shows a further exemplary embodiment of a band drive
device according to the present disclosure with a
clearance-generating device in a partial illustration of a
strapping head.
[0047] FIG. 19 shows the band drive device from FIG. 18 in an
illustration in which a clearance has been generated between a
counterpart roller and the driven roller that interacts
therewith.
[0048] FIG. 1 shows a strapping apparatus 1 which is equipped with
a controller 2, a supply device 3 for storing and making available
a strapping band, and with a strapping head 5. The strapping head 5
serves inter alia for the generation of an advancement movement and
for the generation of a retraction movement of the strapping band.
Said strapping head is furthermore equipped with a tensioning
device, for imparting a band tension to a band loop, and a
fastening device for generating a fastening on the strapping band.
Furthermore, the strapping apparatus has a band guide 6 by way of
which the band can be mechanically and automatically laid around a
packaged item 7 on a predefined path. A welding and clamping unit
16 is also integrated into the strapping head 5. Aside from the
strapping head 5, these are components that are known per se of
strapping apparatuses.
[0049] The strapping head 5, which is arranged together with the
band guide 6 on a frame 8 and which is separately illustrated in
FIG. 2 has a band drive device 15. Band drive devices are basically
already known, for which reason substantially the differences in
relation to previously known band drive devices will be discussed
below. The band drive device according to this exemplary embodiment
may be equipped in particular with one or more roller pairs 11, 12;
13 and possibly with further individual diverting rollers. The
latter however do not participate in the generation of the band
movement and are provided only for determining the band running
direction. Of the three rollers 11, 12, 13 in the exemplary
embodiment which generate the band movements, at least one of the
rollers 11, 12, 13 should be motor-driven for the purposes of
generating a band advancement or band retraction movement. Here, in
each case one roller 11, 12, 13 of the roller pairs formed from
said rollers, between which roller pairs the strapping band is led
through and in the process an advancement, retraction or tensioning
movement, and possibly a tension-relieving movement, is transmitted
to the band, should be driven.
[0050] The strapping head 5 has two components: a control component
16 and a band handling component 17. In the exemplary embodiment,
the control component 16, aside from the execution of control
functions for the components of the strapping device, has further
functions, for example the generation of fastenings between the two
belt layers of a strap and the cutting of the strapping band from
the band supply. The control component 16 is in this case mounted
on a partial carrier 18 of the strapping head, wherein the partial
carrier 18 is in turn detachably fastened to a common main carrier
19 of the strapping head 5. As can be seen in particular from FIG.
4, the partial carrier 18 of the control component 16 is pivotable
about an axis 23. The elements of the band handling component 17
are fastened, without a dedicated partial carrier, directly to the
main carrier 19 of the strapping head. In the exemplary embodiment,
the control component 16 is provided substantially for performing
control and coordination functions out of the functions performed
by the strapping head. The band handling component 17 and the
components attached thereto are, by contrast, provided for acting
directly on the strapping band.
[0051] A band advancement device 20, a band retraction device 21
and a tensioning device 22 are integrated into the band handling
component 17 of the strapping head 5. In the exemplary embodiment
shown here, common rollers 11, 12; 13 are provided for the band
advancement, band retraction and tensioning devices 20, 21, 22. Of
the total of only three rollers 11, 12, 13, two rollers 11, 12 are
motor-driven rollers. The two rollers 11, 12 are driven by the same
(only one) motor 14, in the exemplary embodiment an electric motor.
For this purpose, it may for example be provided that, from the
common motor 14, in each case one drive train leads to one of the
two rollers 11, 12. Here, the roller 11 is provided both as a drive
wheel for the band advancement (band advancement wheel) and as a
drive wheel for the band retraction (band retraction wheel). In
order that, in the exemplary embodiment illustrated, said two
functions can be performed by way of only one wheel, the roller 11
can be driven in both directions of rotation by the same drive
motor 14. Here, in the illustration of FIG. 6, the direction of
rotation counterclockwise is the band advancement direction, and
the direction of rotation clockwise is the band retraction
direction. As shown in FIG. 2, the motor drive movement is
transmitted to both wheels or rollers 11, 12 by the common motor 14
by way of a mechanism device. In the present exemplary embodiment,
the mechanism device 14a comprises a toothed-belt mechanism which
transmits the drive movement from the motor shaft to a further
shaft running parallel to the motor shaft. On said further shaft
there are arranged two gearwheels which belong in each case to a
further one of two partial mechanisms of the mechanism device. One
of said two partial mechanisms of the mechanism device transmits
the motor drive movement to the roller or the wheel 11, and the
other partial mechanism transmits the motor drive movement to the
tensioning wheel 12. Depending on the direction of rotation of the
motor shaft, it is thus the case in the exemplary embodiment that
both the tensioning wheel 12 and the wheel 11 rotate in different
directions of rotation.
[0052] In the installed position of the strapping head depicted in
FIGS. 5 and 6, the roller 11 is arranged above the roller 12. The
roller 12 is a constituent part of the tensioning device 22 and has
the function of the tensioning wheel. Said roller has a
considerably greater diameter than the roller 11. The tensioning
wheel 12, owing to the rigid connection to the motor 14 and the
drive movements in both directions of rotation performed by the
motor, can likewise be driven in both directions of rotation. For
the imparting of the intended band tension to the strapping band,
in particular to the band loop, the tensioning wheel however
utilizes only the drive movement in the tensioning direction, that
is to say the clockwise direction of rotation as viewed in the
illustration of FIG. 6. In certain embodiments, a release of
tension from the band section which is situated in the strapping
head, and which is no longer part of the band loop, may be realized
by way of a rotational movement of the tensioning wheel, taking
place after the tensioning process, in the direction of rotation
opposite to that during the tensioning process. The drive movements
both for the tensioning movement and for the tension-relieving
movement originate from the same drive motor as for the roller 11.
As an alternative to the exemplary embodiment of the present
disclosure illustrated here, it is possible in other embodiments
for a switchable clutch to be provided in the drivetrain (not
illustrated in any more detail) from the motor to the two rollers
11, 12, by way of which clutch the drive movement can be conducted
either to the roller 11 or to the roller 12. Aside from embodiments
in which the tensioning wheel is in turn capable of being driven in
both directions of rotation, it may also be provided that the
tensioning wheel can also be driven only in the direction of
rotation provided for the tensioning process.
[0053] As can be seen from the illustration of FIG. 6, the roller
13 is adjacent both to the roller 11 and to the tensioning wheel
12. The roller 13 is not driven in rotation and is pivotably
articulated by way of a pivoting device. The pivoting device is
operatively connected to a drive by way of which the roller can
perform (motor-) driven pivoting movements. By way of the pivoting
movement, the roller 13 which functions as counterpart roller can
be placed either in contact with the roller 11 or in contact with
the tensioning wheel 12, wherein, in the respective end position of
the pivotable roller 13, the strapping band is situated in each
case between one of the rollers 11, 12 and the roller 13. Depending
on which of the rollers 11, 12 the counterpart roller 13 bears
against, the counterpart roller 13 then forces the band against the
corresponding roller 11, 12 such that the corresponding roller 11,
12 can transmit its rotational movement with the least possible
slippage as an advancement, retraction or tensioning movement, and
possibly as a tension-relieving movement, to the strapping band.
The counterpart roller 13 is thus, together with the roller 11,
both a constituent part of the band advancement device and a
constituent part of the band retraction device. Together with the
tensioning wheel 12, the counterpart roller 13 is also a
constituent part of the tensioning device 22. By way of this
configuration according to the present disclosure, it is possible
for the fourth roller that has hitherto been conventional in
previously known solutions to be dispensed with. In the case of
said previously known solutions, the drive roller and the
tensioning wheel are in each case fixedly assigned one of two
counterpart rollers. The 3-roller solution according to the present
disclosure can permit a considerably more compact embodiment in
relation thereto.
[0054] The rollers 11, 12, 13 are, in the strapping head 5,
furthermore a constituent part of a band guide channel 28 which
predefines the profile and the advancement and retraction path of
the band. The band guide channel 28 is in turn part of the band
guide 6. As can be seen in FIG. 6, the strapping head 5 has a first
interface 29 at which the strapping head 5 adjoins the supply roll
side of the band guide. That end of the band guide channel 28 which
is formed here is in the form of a quick-change interface. This has
a channel piece 31 which can be clamped to the strapping head by
way of a pivotable clamping lever 30 and through which the band is
supplied into the strapping head. The channel piece 31 ends
directly in front of the circumferential surface 11a of the roller
11, such that the strapping band can be supplied at least
approximately tangentially to the circumferential surface 11a of
the roller 11. If the roller 13 is situated in its end position in
which it is pivoted toward the roller 11, the band is led through
between the rollers 11, 13, wherein the roller 13 forces the band
against the roller 11.
[0055] As viewed in the band advancement direction 32, the band
passes, in its further progression, to the tensioning wheel 12.
Here, proceeding from the counterpart roller 13, a
circular-arc-shaped channel section 28a which extends over
approximately 180.degree. of the circumference of the tensioning
wheel 12 is formed by way of suitable channel-forming means. With
regard to the band thickness, the channel section 28a is formed so
as to be considerably wider than the band thickness. The inner
delimitation of the channel section is formed by that section of
the circumferential surface 12a of the tensioning wheel 12 which is
situated in each case in the region of the channel section. The
outer delimitation of the channel section 28a as viewed radially
has guide plates and an outer channel segment which is pivotable
together with the counterpart roller 13, by way of which outer
channel segment the outer channel section can be kept closed
despite the pivotable counterpart roller 13 being situated in the
region of the outer channel section. Without the pivotable channel
segment 33 or some other element of similar action, there would
possibly be an open point of the channel section at least in one of
the two pivoting end positions of the counterpart roller 13, which
open point could possibly have an adverse effect with regard to
reliable band guidance.
[0056] FIGS. 7, 8 and 9 show the tensioning wheel in three
illustrations. Said tensioning wheel has a ring 37 which is
equipped with a recess 38 which is provided for the connection of
the tensioning wheel 12 to a shaft of the drive, in particular to a
shaft of a mechanism of the drive. FIG. 2 shows the tensioning
wheel 12 mounted on the shaft. As can likewise be seen from FIG. 6,
the circular tensioning wheel has a circumferential surface 12a
with an at least substantially constant width. The tensioning wheel
12 is equipped, on its circumferential surface 12a, with a knurling
or toothing 39 by way of which the engagement conditions of the
tensioning wheel 12 on the strapping band are improved. Instead of
a knurling or toothing 39, it would also be possible for any other
geometrically defined or undefined roughening of the
circumferential surface 12a of the tensioning wheel to be provided,
by way of which possible slippage between the tensioning wheel and
the strapping band during the tensioning process can be at least
substantially prevented.
[0057] A groove 40 with a relatively small width is formed over the
entire circumference of the circumferential surface 12a at least
approximately centrally--in relation to the width of the tensioning
wheel 12--and so as to be spaced apart from the lateral edges of
the tensioning wheel, which groove is formed so as to be
considerably deeper than it is wide. In the exemplary embodiment,
two resiliently elastic O-rings 43, 44 are situated one above the
other in the groove 40, said O-rings being arranged radially one
behind the other in the groove 40. Here, one of the O-rings 43 is
arranged with a relatively small spacing to the axis of rotation of
the tensioning wheel 12, and the other O-ring 44 is arranged with a
relatively large spacing to the axis of rotation of the tensioning
wheel 12. The width of the O-rings 43, 44 is in this case provided
so as to approximately correspond to the width of the groove 40.
The two O-rings 43, 44 are situated entirely within the groove 40.
The two O-rings 43, 44 are formed from resiliently elastic
material.
[0058] On the outer of the two O-rings 43, 44 there is seated a
ring 45 which is provided as a spacer element and which, in the
exemplary embodiment, is formed from a metallic material. In this
exemplary embodiment, the ring 45 is elastically deformable. It
would likewise be possible for the ring to be of substantially
rigid or dimensionally stable form. To realize said elastic
characteristics of the ring, it would also be possible for the ring
45 to be formed from one or more materials other than a metallic
material, for example from an elastic plastic. In the exemplary
embodiment, said metal ring 45 is, in terms of its cross section,
provided so as to have a width B smaller than its height H. The
height of the O-ring is, with regard to the groove depth and the
height of the O-rings, configured such that the ring projects with
a height H.sub.1 out of the groove 40. Thus, in its unloaded state
shown in FIG. 9, the ring 45 projects beyond the circumferential
surface 12a of the tensioning ring 12, in particular over its
entire circumference or over the entire circumference of the
tensioning ring 12.
[0059] At the start of the strapping process, the strapping band is
pushed at high speed, with its free band end first, from the
strapping head 5 through the band guide 6. For this purpose, the
counterpart roller 13 is in contact with one side of the band. The
band is forced with its other side against the motor-driven roller
11 by the counterpart roller. The rotational drive movement of the
roller 11 in the advancement direction is in this way transmitted
to the strapping band, which effects the advancement movement
thereof in the advancement direction. Downstream of the region in
which the band emerges from the gap between roller 11 and
counterpart roller 13, the band comes into contact with the
tensioning wheel 12, but without exerting a significant pressure on
the tensioning wheel 12.
[0060] After the band has been pushed all the way through the band
guide 6, the band end reaches the closure head again. Here, the
band end actuates a limit switch, whereby the advancement movement
is stopped and the band end is clamped. These and other activation
and deactivation processes of components of the closure head are
performed by the control component 16 which, for this purpose, is
equipped with a motor-driven camshaft control arrangement such as
is basically known.
[0061] The camshaft control arrangement of the control component 16
now sets the roller 11 in motion in a direction of rotation
reversed in relation to the advancement direction. The strapping
band, which remains clamped between the roller 11 and the
counterpart roller 13, is hereby moved in the reverse direction,
that is to say in the band retraction direction 48. The
circumferential length of the band loop, the band end of which
remains clamped, is hereby continuously shortened. The band is
hereby pulled out of the band guide 6 and, as a result, laid around
the respective packaged item.
[0062] FIG. 6 illustrates the tensioning wheel 12 during the band
retraction process. As can be seen from said illustration, it is
the case during the band retraction process that the band comes
into contact with the tensioning wheel 12. The strapping band bears
against the tensioning wheel 12 substantially over the entire
circular-arc-shaped channel section 28a, similarly to the situation
also encountered during the subsequent tensioning process. The band
is duly retracted here, but, owing to its ability to yield to said
movement by moving, as intended, out of the band guide, it is
nevertheless the case during said phase that only a relatively low
band tension is applied to the band of the band loop. As a result
of said contact with the tensioning wheel 12 and of the ring 45
which projects in relation to the circumferential surface, the band
bears not against the circumferential surface of the tensioning
wheel 12 but against the ring 45 situated in the circumferential
surface 12a. Said contact with the spacer element, which, in the
exemplary embodiment, is in this case in the form of a ring 45, has
the effect that, during the band retraction, the band cannot be
damaged by the knurling or toothing 39 of the circumferential
surface 12a.
[0063] After the band has been laid against the packaged article as
a result of the band retraction, the controller switches from band
retraction to generation of a band tension, whereby it is the
intention for the band laid against the packaged article to be
pulled taut. For this purpose, it is firstly the case that the
counterpart roller 13 is pivoted from its position of contact
against the roller 11 into a position of contact against the
tensioning wheel 12. The tensioning wheel 12, which is rotated in
the same direction of rotation as the roller 11 was previously,
rotates at a lower rotational speed but with a greater torque, and
pulls further on the strapping band. Owing to the absence of
pressure of the counterpart roller 13, it is by contrast now the
case that the band no longer bears against the roller 11, which
continues to be driven in the exemplary embodiment and which
rotates at a higher speed, in such a way that the roller 11 could
transmit its movement to the band. Since, at this stage, the
strapping band already bears against the packaged article, the band
is, by the tensioning wheel 12, retracted at most over a short
length in relation to the band retraction phase. During said
tensioning phase, it is in particular the case that a relatively
high band tension is applied to the band.
[0064] Already at the start of the tensioning phase, the pressure
of the counterpart roller 13 in the direction of the tensioning
wheel and the band situated in between causes the ring 45 to be
forced in the direction of the groove base and thus also in the
direction of the axis of rotation of the tensioning wheel 12 as
viewed in a substantially radial direction. In this way, it is the
case already at the start of the tensioning phase that the band
bears against the ring 45 and forces the latter likewise, at least
in the region of the counterpart roller 13, in the direction of the
groove base. Thus, already at the start of the tensioning process,
the ring 45 has, in the region of the counterpart roller 13, a
smaller spacing to the axis of rotation of the tensioning wheel
than in its unloaded state, for example during the band advancement
or the band retraction phase.
[0065] The torque transmitted from the tensioning wheel 12 to the
band during the further course of the tensioning process, which
torque is higher than that in the band retraction phase of the
roller 11, results in a greater reaction force of the band. Said
greater reaction force now has the effect that the band forces the
ring 45 into the groove not only in the contact region with the
counterpart roller 13 but over its contact length (wrap angle as
viewed in the circumferential direction) with the ring 45, whereby
the band now bears, along its wrap angle on the tensioning wheel
12, against the circumferential surface of said tensioning wheel.
Along its wrap angle on the tensioning wheel, the band forces the
ring into the groove counter to the spring forces of the O-rings.
Depending on the characteristics of the ring 45, said ring is
deformed possibly elastically as a result, and, along that
circumferential section in which the strapping band does not bear
against the tensioning wheel, said ring can partially (with regard
to its height) emerge from the groove again. Outside the wrap angle
of the band on the tensioning wheel, the ring 45 may in this case
project out of the circumferential surface to a greater extent than
in the unloaded state, in the case of which it projects with a
height H. Since the ring is arranged rotationally conjointly in the
groove, it is the case, in a manner dependent on the respective
rotational position of the tensioning wheel 12, that each
individual point of the ring is forced into the groove 40, and
emerges from said groove again, in alternating fashion until, owing
to the rotation of the tensioning wheel, said point arrives again
at the point at which the band wraps around a section of the
circumferential surface and thereby forces the ring into the groove
along said section. It is thus possible, despite the means provided
for preventing the strapping band from coming into contact with the
circumferential surface of the tensioning wheel during the band
retraction phase, for functionally reliable contact of the band
with the same tensioning wheel to nevertheless be achieved during
the band tensioning phase.
[0066] The counterpart roller 13 can advantageously be forced with
different pressing forces firstly against the roller 11
(advancement roller or retraction roller) and secondly against the
tensioning wheel 12 (during the use of the strapping device in each
case with a strapping band situated in between). Higher pressing
forces against the tensioning wheel than the possible pressing
forces against the roller 11 can be advantageous for high
functional reliability and for the possibility of applying high
band tensions to the strapping band. Therefore, below, it will be
discussed how, in one embodiment of the present disclosure, despite
the pivoting movement of the counterpart roller 13 between two end
positions, different pressing forces can be realized in the end
position.
[0067] For this purpose, the counterpart roller 13 is arranged on
an eccentric 50 which, in turn, is arranged on a shaft 51 of a
carrier 52. The carrier has, spaced apart from the shaft 52, a
receptacle 53 which is provided for arrangement on the bearing
point 54 of the roller 11 (FIGS. 5 and 6). Here, the receptacle 53
is freely rotatable about its axis of rotation on the bearing point
54 of the roller 11 and can thus perform pivoting movements about
its axis of rotation.
[0068] In the region of the counterpart roller 13 and of the roller
11, there is provided a parallelogram which has multiple levers 57,
58, 59 which are pivotably articulated on one another. The
parallelogram 56 has a long vertical lever 57, a horizontal lever
58 and a short vertical lever 59. The parallelogram is pivotably
articulated on the long vertical lever 57 and on the short vertical
lever 59. The levers 57 and 59 have pivot bearing points 60, 61 for
this purpose. Via a bell-shaped curve 62, it is possible for a
rotational movement to be transmitted to the long vertical lever
57, which rotational movement leads to the pivoting movement of the
lever 57 about its pivot bearing point 60. In the illustration of
FIG. 12, the pivoting movement of the lever 57 takes place
clockwise.
[0069] In this way, at the articulation point of the short vertical
lever, the lever 58 also pulls said short vertical lever in the
direction of the lever 57, whereby the vertical lever 59 is, in the
illustration of FIGS. 11 and 12, likewise pivoted clockwise about
its pivot bearing point 62. As a result, an oblique surface 64
formed on the short vertical lever 59 pushes against a bearing 51
arranged on the shaft 51. As a result, the oblique surface performs
a movement clockwise (in the illustration of FIG. 12) and has the
tendency to assume a horizontal orientation. As a result, the
carrier 52 performs a pivoting movement, whereby the counterpart
roller 13 is pivoted from its end position against the roller 11 in
the direction of the tensioning wheel 12.
[0070] When it reaches the tensioning wheel, the counterpart roller
bears against the tensioning wheel and can perform no further
pivoting movement. The lever 57 however pivots further, whereby the
bearing point 65 of the eccentric 50 is moved counterclockwise in
the direction of an L-shaped carrier 66. After the bearing point 65
pushes against the L-shaped carrier 65, the movement of the bearing
point 65 stops, and said bearing point is situated at least
approximately in a line with an upper bearing point 66, the axis of
rotation 67 of the counterpart roller 13 and the axis of rotation
68 of the tensioning wheel 12. A spring element that has hitherto
generated the pressing force of the counterpart roller 13 is, as a
result, no longer active.
[0071] A further movement of the lever 57 during its pivoting
movement now has the effect that the lever 59 can also perform no
further movement, and therefore two parts 58a and 58b of the
horizontal lever 58 are pulled apart. A spring element 70 arranged
between the two parts 58a, 58b of the lever is hereby compressed,
whereby the spring force thereof increases. This leads to a torque
of the lever 59 about the pivot bearing point 61 with the lever arm
of the spacing of the pivot bearing point 61 from the articulation
point 71 of the lever 58 on the lever 59. As a result, the oblique
surface 64 pushes, in the form of a torque about the pivot bearing
point 61, against the bearing, which now leads to a pressing force
of the roller 13 against the tensioning wheel. By way of a
correspondingly dimensioned and designed spring element 70 and
corresponding lever ratios, it is possible in this way to realize
high pressing forces of the roller 13 against the tensioning
wheel.
[0072] A restoration of the parallelogram can be realized by way of
a further spring 73 arranged on the peg 72 of the lever 5.
[0073] Alternative embodiments of components and assemblies
discussed above will be described below. Here, substantially only
differences in relation to the corresponding components from FIGS.
1 to 13 will be discussed. Where said embodiments include identical
or similar configurations to those in the exemplary embodiment of
FIGS. 1 to 13, these will not be discussed in any more detail
below; the content of disclosure of the exemplary embodiments of
FIGS. 1 to 13 is however also incorporated by reference for the
exemplary embodiments of FIGS. 14 to 19.
[0074] FIGS. 14, 15, 16 and 17 illustrate a further embodiment of a
tensioning wheel 112 according to the present disclosure. The
tensioning wheel 112 may be divided longitudinally in terms of its
width, approximately in the center, wherein the two parts 112b,
112c of the tensioning wheel 112 are detachably connectable to one
another by way of suitable fastening elements, for example screws
114. In the region of said parting plane, which need not run in a
flat manner, an encircling groove 140 is formed in the outer ring
137 of the tensioning wheel 112, which groove is open toward the
circumferential surface 112a of the tensioning wheel 112 and is
narrowed or decreased in size toward said circumferential
surface.
[0075] One or more restoring elements may be arranged in the groove
140. In the exemplary embodiment, as a restoring element, there are
arranged elastic ring sections 143, for example multiple
resiliently elastic O-ring sections 143. Said ring sections are
distributed in the groove 140 at regular intervals with respect to
one another, as is the case in the exemplary embodiment with a
total of four ring sections 143. The restoring elements 143 are
situated below one or more spacer elements. In the exemplary
embodiment, only one spacer element 145, in the form of a closed
ring, is provided. An outer diameter of the ring 145 arranged in
the groove is in this case dimensioned such that, in the unloaded
state of the ring 145, said ring projects with its outer
circumferential surface beyond the circumferential surface 112a of
the tensioning ring 112. The ring 145 is situated with its inner
circumferential surface in the groove. The restoring elements are
attached to the inner circumferential surface of the circular and
substantially dimensionally stable ring 145. In other embodiments,
it is also possible for a different number of spacer elements, and
a different number of restoring elements, to be provided.
[0076] As a result of contact of the strapping band against the
ring 145, and as a result of a certain minimum pressure force being
exerted on the ring along a certain angle range along a section of
the circumference of the tensioning wheel by the strapping band, it
is possible for approximately that section of the ring 145 which
projects beyond the groove along said angle range to be forced into
the groove 140, such that, in said positionally static angle range
of the tensioning wheel 112, the strapping band comes into contact
with the circumferential surface 112a of the tensioning wheel 112
and can be driven along by the circumferential surface 112a during
the movement of the tensioning wheel 112. The ring 145, which
substantially cannot be deformed by the expected forces acting
thereon in the exemplary embodiment, and which is thus
dimensionally stable, is thus arranged slightly eccentrically in
relation to the axis of rotation of the tensioning wheel during
said process. The ring 145 hereby projects, with its section not
encompassed by the wrap angle of the band, out of the groove 140
further than when the tensioning wheel is in the state in which it
is not subject to load by the strapping band. As a result of the
ring 145 being relieved of the load of the strapping band, or when
a pressure force exerted on the ring 145 by the strapping band is
not sufficient, it is possible, after the completion of the
tensioning process, for the elastic restoring forces of one or more
of the ring sections 143 to cause the ring 145 to project out of
the groove again over its entire circumference.
[0077] By way of this arrangement, it is possible, during the
tensioning process, during which the tensioning band exerts an
adequately high pressure force on the ring 145 situated in the wrap
region of the strapping band, for the ring 145 to be forced in
sections into the groove 140. During the retraction process, during
which only a relatively low tensile stress is present in the
strapping band, the pressure force on that section of the ring 145
which is presently arranged in the wrap region of the band is not
high enough to force said ring section entirely into the groove
140. As a result, the band bears against the section of the ring
145 and not against the surface of the tensioning wheel 112. The
ring 145 holds the strapping band so as to be spaced apart from the
circumferential surface of the tensioning wheel 112.
[0078] FIGS. 18 and 19 illustrate a further exemplary embodiment of
a band drive device 115. Said band drive device also has only three
rollers 111, 112, 113 which are responsible for imparting the band
advancement, band retraction and band tensioning movements to the
band by way of contact with the band, wherein the two rollers 111
and 112 can be driven by way of a motor, in particular by way of
only one common motor. The relative arrangement of the axes of
rotation of the three rollers 111, 112, 113 with respect to one
another corresponds at least approximately to the arrangement of
said axes of rotation in the exemplary embodiment of FIGS. 5 and
6.
[0079] The counterpart roller 113 is again designed to be
pivotable, such that, in one pivoting position, it is provided for
pressing the strapping band against the roller 111, and in another
pivoting position, it is provided for pressing the strapping band
against the tensioning roller 112. The pivoting mechanism, provided
for this purpose, of the counterpart roller 113, and the drive of
said pivoting mechanism, may in principle be of the same design as
in the exemplary embodiment of FIGS. 1 to 13. As in the exemplary
embodiment of FIGS. 5 and 6, the counterpart roller 113 is
rotatably mounted on an eccentric 150, such that the counterpart
roller 113 performs a non-circular-arc-shaped movement during a
pivoting movement from one of the rollers 111, 112 to the
respective other roller 111, 112. As shown in FIGS. 18 and 19, a
clearance-generating device 180 is mounted on the eccentric 150 of
the counterpart roller 113, wherein the clearance-generating device
180 is supported with a carrier 181 on the frame of the strapping
apparatus 101. The bearing point 182 of the clearance-generating
device on the eccentric 150 is itself arranged pivotably on the
eccentric, and is in the form of a C-shaped or fork-shaped element
183 to thereby form a receptacle for one end of a piston 184. Said
piston 184 is arranged in displaceable fashion in the carrier 181
of the clearance-generating device 180. In the illustration of
FIGS. 18 and 19, the support point is situated immediately above
the roller 111. The carrier 181 of the clearance-generating device
is in this case likewise mounted in pivotable fashion.
[0080] In the exemplary embodiment shown, the clearance-generating
device 180 is equipped with a clearance-generating element which is
provided for performing a controlled movement by way of which the
counterpart roller 113 is acted on in order for the counterpart
roller 113, in its pivoted edition against the roller 111, to be
moved such that a clearance is generated, or to be lifted slightly.
The counterpart roller 113, in its pivoted position at the roller
111, should, even after the generation of a clearance, be able to
be placed against the roller 111 again, for example likewise by way
of the clearance-generating device. In the exemplary embodiment,
the clearance-generating element is in the form of a solenoid 186
which is arranged and mounted on the clearance-generating device
180. The solenoid 186 can, by way of its piston 184, perform a
linear stroke movement along the longitudinal axis 184a of its
piston 184. As shown in FIGS. 18 and 19, one end of the piston 184
is arranged in the recess, which is open toward the carrier 181, of
the C-shaped or fork-shaped element 183. The end of the piston 184
and the recess of the C-shaped element may in this case be designed
such that, during the clearance-generating movement, the end of the
piston 184 in the C-shaped element can move relative thereto.
[0081] Here, the extended longitudinal axis 184a of the piston 184
runs at least approximately through the articulation point of the
C-shaped element 183. A stroke movement of the piston 184 in the
direction of the counterpart roller 113 thus leads to a rotational
movement of the eccentric about its axis of rotation. In the
illustration of FIG. 18, the rotational movement takes place
counterclockwise, as can be seen from a comparison of the two FIGS.
18 and 19. The rotational movement of the eccentric 150 in turn has
the effect that the axis of rotation of the counterpart roller 113
is displaced in parallel and a gap, or an enlarged gap, is formed
between the roller 111 and the counterpart roller 113. The width of
the gap should in this case have a size greater than the thickness
of the strapping band being processed in each case. As a solenoid,
use may for example be made of the product GKb-32.06 from the
company Isliker Magnete AG, CH-8450 Andelfingen.
[0082] On the piston 184 there may be arranged a mechanical spring
element, in particular at least one compression spring 188. Said
compression spring 188 is compressed, and thus braced in
resiliently elastic fashion, during the movement of the counterpart
roller 113 from the tensioning roller 112 into contact with the
roller 111. The electrically actuable magnetic stroke-performing
piston is deactivated, and thus has no action, in this phase.
During the stroke movement, the compression spring 188 is at least
partially relaxed and the spring force acts so as to assist the
force imparted by the solenoid, by way of which force the piston
184 is moved so as to generate a clearance between the counterpart
roller 113 and the roller 111. In other exemplary embodiments, in
which the solenoid or some other restoring element alone provides a
force high enough for the clearance-generating process.
[0083] During the production of the strap, it is the case--as
already described--that, by way of the roller 111 and the
counterpart roller 113 which bears against the former roller and
clamps the band between the two rollers, the band is moved through
the band guide channel 28 in a feed direction. When the strapping
band reaches the region of the end of the band guide channel, as is
illustrated by way of example in highly schematized form in FIG. 1,
the band strikes a stop, or the fact that the end of the band guide
channel has been reached may be detected in some other way, for
example by way of a light barrier. In this way, a signal is
generated, by way of which the control of the strapping apparatus
stops the motor drive movement of the roller 111 and--at least
substantially at the same time--triggers the stroke movement of the
piston 184 of the solenoid. In other embodiments of the present
disclosure, it is also conceivable for the stoppage of the drive
movement of the roller 111 and the start of the
clearance-generating process to have a time offset with respect to
one another, that is to say for the stoppage of the drive movement
to be performed before or after the start of the
clearance-generating process.
[0084] As a result of the starting of the clearance-generating
process, the piston 184 deploys in the direction of the C-shaped
element 183 and, here, acts by way of its end on the C-shaped or
fork-shaped element. Owing to its arrangement on the eccentric 150,
the eccentric is rotated during the stroke movement of the piston.
In the exemplary embodiment and in the illustration of FIG. 18, the
rotational movement of the eccentric takes place through a
rotational angle of less than 90.degree. counterclockwise. The
rotational movement takes place counter to the spring force of the
pressure-exerting spring 190, which in this case is compressed and
is likewise articulated on the eccentric 150. As a result of the
rotational movement, a clearance is generated between the
counterpart roller 113 and the roller 111, that is to say the
counterpart roller 113 is lifted from the roller 111, and the
spacing between the two rollers 111, 113 is enlarged such that a
gap forms between the rollers, which gap is larger than the band
thickness.
[0085] In the case of generic strapping apparatuses, the strapping
band, which is shot at high speed through the band channel of the
band guide 6, has the tendency, owing to the sudden and abrupt
stoppage of the band, to form convolutions between the rollers 111,
112, 113 and the end of the strapping channel. In particular in the
region of the rollers 111, 112, 113, such convolutions can lead to
malfunctions. Owing to the embodiment according to the present
disclosure, in which a clearance of the counterpart roller 113 is
generated, the band can, in particular immediately after the
stoppage of the advancement, move freely counter to the advancement
direction in the direction of the band supply to the extent
required for that part of the band which is possibly excess in
relation to the length of the band channel, and which causes the
formation of convolutions, to move back in the band guide channel.
The controller of the strapping apparatus can then subsequently
deactivate the solenoid again. As a result, the solenoid is
rendered inactive, whereby the pressure-exerting spring 190 can
move the eccentric 150 back again counter to the previous direction
of rotation, and thus move the counterpart roller 113 into its
position of contact with the band again, in which the band is
clamped between the roller 111 and the counterpart roller 113. The
subsequent band retraction and tensioning process can be performed
in the same way as in the embodiments of the present disclosure as
per FIGS. 1 to 13.
TABLE-US-00001 List of reference designations 1 Strapping apparatus
2 Controller 3 Supply device 5 Strapping head 6 Band guide 8 Frame
11 Roller 11a Circumferential surface 12 Tensioning wheel 12a
Circumferential surface of tensioning wheel 13 Counterpart roller
14 Motor 14a Mechanism device 15 Band drive device 16 Control
component 17 Band handling component 18 Partial carrier 19 Main
carrier 20 Band advancement device 21 Band retraction device 22
Tensioning device 23 Axle 27 Pivoting device 28 Band guide channel
28a Channel section 28b Outer delimitation 29 Interface 30 Clamping
lever 31 Channel piece 32 Band advancement direction 33 Outer
channel segment 37 Ring 38 Recess 39 Knurling/toothing 40 Groove 43
O-ring 44 O-ring 45 Ring 48 Band retraction direction 50 Eccentric
51 Shaft 52 Carrier 53 Receptacle 54 Bearing point 56 Parallelogram
57 Long vertical lever 58 Horizontal lever 59 Short vertical lever
60 Pivot bearing point 61 Pivot bearing point 64 Oblique surface 65
Bearing point 66 Carrier 67 Rotary axle 68 Rotary axle 70 Spring
element 71 Articulation point 72 Peg 101 Strapping apparatus 111
Roller 112 Tensioning wheel 112a Circumferential surface 112b Part
112c Part 113 Counterpart roller 114 Screw 115 Band drive device
137 Ring 140 Groove 143 Ring section 145 Ring 150 Eccentric 180
Clearance device 181 Carrier 182 Bearing point 183 C-shaped element
184 Piston 184a Axis 186 Solenoid 188 Compression spring 190
Pressure-exerting spring B Width H Height H.sub.1 Height
* * * * *